U.S. patent application number 12/569344 was filed with the patent office on 2010-04-08 for special polyether-based polyurethane formulations for the production of holographic media.
This patent application is currently assigned to Bayer MaterialScience AG. Invention is credited to Friedrich-Karl Bruder, Thomas Facke, Jorg Hofmann, Dennis Honel, Klaus Lorenz, Thomas Roelle, Marc-Stephan Weiser.
Application Number | 20100086861 12/569344 |
Document ID | / |
Family ID | 40377496 |
Filed Date | 2010-04-08 |
United States Patent
Application |
20100086861 |
Kind Code |
A1 |
Weiser; Marc-Stephan ; et
al. |
April 8, 2010 |
SPECIAL POLYETHER-BASED POLYURETHANE FORMULATIONS FOR THE
PRODUCTION OF HOLOGRAPHIC MEDIA
Abstract
The present invention relates to novel polyurethane compositions
which are advantageous for the production of holographic media,
inter alia for data storage, but also for optical applications of
different types.
Inventors: |
Weiser; Marc-Stephan;
(Leverkusen, DE) ; Roelle; Thomas; (Leverkusen,
DE) ; Bruder; Friedrich-Karl; (Krefeld, DE) ;
Facke; Thomas; (Leverkusen, DE) ; Honel; Dennis;
(Zulpich, DE) ; Lorenz; Klaus; (Dormagen, DE)
; Hofmann; Jorg; (Krefeld, DE) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ, LLP
P O BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
Bayer MaterialScience AG
Leverkusen
DE
|
Family ID: |
40377496 |
Appl. No.: |
12/569344 |
Filed: |
September 29, 2009 |
Current U.S.
Class: |
430/2 ;
522/97 |
Current CPC
Class: |
C08G 18/4866 20130101;
C08G 18/776 20130101; G11B 7/245 20130101; C08G 18/7837 20130101;
G03F 7/001 20130101; G03F 7/035 20130101; C08G 18/7887 20130101;
C08G 18/672 20130101; G11B 7/24044 20130101; G03F 7/027
20130101 |
Class at
Publication: |
430/2 ;
522/97 |
International
Class: |
C08G 18/67 20060101
C08G018/67; G03H 1/04 20060101 G03H001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2008 |
EP |
08017278.6 |
Claims
1. A polyurethane composition comprising A) a polyisocyanate
component; B) an isocyanate-reactive component comprising a
hydroxy-functional multiblock copolymer B1) of the type
Y(X.sub.i--H).sub.n having a number average molecular weight of
greater than 1000 g/mol; wherein X.sub.i is an oxyalkylene units of
formula (I): --CH.sub.2--CH(R)--O-- (I); i is an integer from 1 to
10; n is an integer from 2 to 8; R is a hydrogen, alkyl, or aryl
radical, wherein said alkyl or aryl radical is optionally
substituted or interrupted by a heteroatom; and Y is the
fundamental initiator and the proportion of the segments X.sub.i,
based on the total amount of the segments X.sub.i and Y, accounts
for at least 50% by weight; C) a compound free of NCO groups which
comprises a group that reacts under the action of actinic radiation
with ethylenically unsaturated compounds via polymerization; D)
free radical stabilizers; E) photoinitiators; F) optionally
catalysts; and G) optionally auxiliaries and additives.
2. The polyurethane composition of claim 1, wherein A) comprises a
polyisocyanate and/or a prepolymer based on HDI, TMDI, and/or
TIN.
3. The polyurethane composition of claim 1, wherein A) comprises a
polyisocyanate based on HDI with isocyanurate and/or
iminooxadiazinedione structures or prepolymers having an NCO
functionality of from 2 to 5 and exclusively primary NCO
groups.
4. The polyurethane composition of claim 1, wherein A) has a
residual content of free monomeric isocyanate of less than 0.5% by
weight.
5. The polyurethane composition of claim 1, wherein at least one
segment X, is a propylene oxide-based homopolymer or random or
block copolymer comprising oxyethylene, oxypropylene and/or
oxybutylene units, wherein the proportion of said oxypropylene
units, based on the total amount of all oxyethylene, oxypropylene,
and oxybutylene units, accounts for at least 20% by weight.
6. The polyurethane composition of claim 1, wherein said starter
segment Y is based on a difunctional, aliphatic polycarbonate
polyol, poly(.epsilon.-caprolactone), or polymer of tetrahydrofuran
having a number average molar mass greater than 250 g/mol and less
than 2100 g/mol.
7. The polyurethane composition of claim 1, wherein said multiblock
copolymers B1) has a number average molecular weight of from 1200
to 12 000 g/mol.
8. The polyurethane composition of claim 1, wherein said compound
of C) has a refractive index n.sub.D.sup.20 of greater than
1.55.
9. The polyurethane composition of claim 1, wherein C) comprises a
urethane acrylate and/or a urethane methacrylate based on an
aromatic isocyanate and 2-hydroxyethyl acrylate, hydroxypropyl
acrylate, 4-hydroxybutyl acrylate, polyethylene oxide
mono(meth)acrylate, polypropylene oxide mono(meth)acrylate,
polyalkylene oxide mono(meth)acrylate, and/or a
poly(.epsilon.-caprolactone) mono(meth)acrylate.
10. A process for producing media for recording visual holograms
comprising (1) applying the polyurethane composition of claim 1 to
a substrate or in a mould and (2) curing said polyurethane
composition.
11. A medium for recording visual holograms produced by the process
of claim 10.
12. An optical element or image comprising the medium of claim
11.
13. A method for recording a hologram comprising exposing the
medium of claim 12.
Description
RELATED APPLICATIONS
[0001] This application claims benefit to European Patent
Application No. 08017278.6, filed Oct. 1, 2008, which is
incorporated herein by reference in its entirety for all useful
purposes.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to novel polyurethane
compositions which are advantageous for the production of
holographic media, inter alia for data storage, but also for
optical applications of different types.
[0003] In the structure of holographic media, as described in U.S.
Pat. No. 6,743,552, information is stored in a polymer layer which
substantially comprises a polymer matrix and very special
polymerizable monomers present in uniform distribution therein.
This matrix polymer may be polyurethane-based. It is prepared
starting from isocyanate-functional materials which are crosslinked
with polyols, such as polyethers or polyesters, with urethane
formation.
[0004] U.S. Pat. No. 6,743,552, U.S. Pat. No. 6,765,061 and U.S.
Pat. No. 6,780,546 disclose polyether-based PU matrices for use in
holographic media, which are substantially based on trifunctional
polypropylene oxides (PPO) and mixtures of poly(THF) with
trifunctional PPO. Some of the formulations described there contain
PPO having a low molar mass (Mn.ltoreq.1000 g/mol) as a mixture
with poly(THF), also having molar masses up to Mn.ltoreq.1500
g/mol. A very similar approach is described in JP 2008015154 A
20080124. Here, the matrix was formed from difunctional isocyanates
and mixtures of poly(THF) and trifunctional PPO. Likewise, US
2003044690 A1 20030306 describes the synthesis of a PU matrix from
Desmodur.RTM. N 3400, Desmodur.RTM. N 3600 or Baytec WE-180 and a
trifunctional PPO based on glycerol, having an Mn of 1000. In
addition, in JP 2008070464 A 20080327, polyether-based PU matrices
having relatively high Tg values (>30.degree. C.) are used for
holographic media. In WO 2008029765 A1 20080313, polyester- and
polycarbonate-based polyols are used as components for polyurethane
matrices for volume holograms and holographic media. WO 2005116756
A2 20051208 describes low-Tg polyurethane matrices based on a
mixture of polyesters and Surfynol 440 (Air Products and Chemicals,
Inc., Allentown, USA), a polyether with alkynediol starter for
embossed holograms.
[0005] Furthermore, the patents JP 2007101743, JP 2007086234, JP
2007101881, US 20070077498 and US 20070072124 describe the use of
di- and trifunctional polypropylene oxide in connection with PU
matrices in the area of holographic data memories or as
"volume-type holographic optical recording media". The isocyanate
component used there was dicyclohexylmethane 4,4'-diisocyanate
("H12-MDI") or a prepolymer of the abovementioned components, in
some cases in the presence of 1,4-butanediol as a chain extender.
Analogous formulations are disclosed in the patents JP 2007187968
and JP 2007272044 for the area of "information recording and
fixation" and "high density volume holographic recording material".
The patent JP 2008070464 describes an analogous formulation as
matrix material for holographic data memories and "holographic
recording materials and recording media". In this case,
polyethylene glycol having a number average molar mass (Mn) of 600
g/mol was used as a chain extender and, in addition to "H12-MDI",
hexamethylene diisocyanate was also used. A trifunctional
polypropylene oxide in combination with hexamethylene diisocyanate
and/or Desmodur.RTM. N3300 was described in the patent JP
2007279585 as matrix material for the production of "holographic
recording layers" and an "optical recording medium".
[0006] However, a disadvantage of the known polyurethane-based
systems, in particular for optical applications outside digital
data storage, is that the achievable brightness of the holograms
stored in such media is too low. The reason for this is in general
that the relative difference between the refractive indices of
polyurethane matrix and writing monomer is too small. On the other
hand, an arbitrary variation of the matrix polymer is not possible
since good compatibility of the matrix polymer with writing monomer
and the further components present in the formulations must always
be ensured. Furthermore, for processing reasons, it is of interest
to ensure that mixing and provision of the formulations are as
simple as possible to carry out.
[0007] It was therefore an object of the invention to provide novel
polyurethane compositions which permit a better contrast ratio and
improved brightness of the holograms without sacrifices with
respect to the compatibilities of matrix polymer and writing
monomer.
[0008] It has now surprisingly been found that the abovementioned
requirements can be met if special polyether polyols are used for
synthesizing the matrix polymer.
EMBODIMENTS OF THE INVENTION
[0009] An embodiment of the present invention is a polyurethane
composition comprising [0010] A) a polyisocyanate component; [0011]
B) an isocyanate-reactive component comprising a hydroxy-functional
multiblock copolymer B1) of the type Y(X.sub.i--H).sub.n having a
number average molecular weight of greater than 1000 g/mol; [0012]
wherein [0013] X.sub.i is an oxyalkylene units of formula (I):
[0013] --CH.sub.2--CH(R)--O-- (I); [0014] i is an integer from 1 to
10; [0015] n is an integer from 2 to 8; [0016] R is a hydrogen,
alkyl, or aryl radical, wherein said alkyl or aryl radical is
optionally substituted or interrupted by a heteroatom; and [0017] Y
is the fundamental initiator and the proportion of the segments
X.sub.i, based on the total amount of the segments X.sub.i and Y,
accounts for at least 50% by weight; [0018] C) a compound free of
NCO groups which comprises a group that reacts under the action of
actinic radiation with ethylenically unsaturated compounds via
polymerization; [0019] D) free radical stabilizers; [0020] E)
photoinitiators; [0021] F) optionally catalysts; and [0022] G)
optionally auxiliaries and additives.
[0023] Another embodiment of the present invention is the above
polyurethane composition, wherein A) comprises a polyisocyanate
and/or a prepolymer based on HDI, TMDI, and/or TIN.
[0024] Another embodiment of the present invention is the above
polyurethane composition, wherein A) comprises a polyisocyanate
based on HDI with isocyanurate and/or iminooxadiazinedione
structures or prepolymers having an NCO functionality of from 2 to
5 and exclusively primary NCO groups.
[0025] Another embodiment of the present invention is the above
polyurethane composition, wherein A) has a residual content of free
monomeric isocyanate of less than 0.5% by weight.
[0026] Another embodiment of the present invention is the above
polyurethane composition, wherein at least one segment X.sub.i is a
propylene oxide-based homopolymer or random or block copolymer
comprising oxyethylene, oxypropylene and/or oxybutylene units,
wherein the proportion of said oxypropylene units, based on the
total amount of all oxyethylene, oxypropylene, and oxybutylene
units, accounts for at least 20% by weight.
[0027] Another embodiment of the present invention is the above
polyurethane composition, wherein said starter segment Y is based
on a difunctional, aliphatic polycarbonate polyol,
poly(.epsilon.-caprolactone), or polymer of tetrahydrofuran having
a number average molar mass greater than 250 g/mol and less than
2100 g/mol.
[0028] Another embodiment of the present invention is the above
polyurethane composition, wherein said multiblock copolymers B1)
has a number average molecular weight of from 1200 to 12 000
g/mol.
[0029] Another embodiment of the present invention is the above
polyurethane composition, wherein said compound of C) has a
refractive index n.sub.D.sup.20 of greater than 1.55.
[0030] Another embodiment of the present invention is the above
polyurethane composition, wherein C) comprises a urethane acrylate
and/or a urethane methacrylate based on an aromatic isocyanate and
2-hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl
acrylate, polyethylene oxide mono(meth)acrylate, polypropylene
oxide mono(meth)acrylate, polyalkylene oxide mono(meth)acrylate,
and/or a poly(.epsilon.-caprolactone) mono(meth)acrylate.
[0031] Yet another embodiment of the present invention is a process
for producing media for recording visual holograms comprising (1)
applying the above polyurethane composition to a substrate or in a
mould and (2) curing said polyurethane composition.
[0032] Yet another embodiment of the present invention is a medium
for recording visual holograms produced by the above process.
[0033] Yet another embodiment of the present invention is an
optical element or image comprising the above medium.
[0034] Yet another embodiment of the present invention is a method
for recording a hologram comprising exposing the above medium.
BRIEF DESCRIPTION OF THE DRAWING
[0035] FIG. 1 depicts the geometry of a holographic media tester at
.lamda.=633 nm (He--Ne laser) for writing a reflection
hologram.
[0036] FIG. 2 depicts a plot of the Bragg curve .eta. according to
Kogelnik (dashed line), of the measured diffraction efficiency
(solid circles) and of the transmitted power (black solid line)
against the angle detuning .DELTA..OMEGA..
DESCRIPTION OF THE INVENTION
[0037] The invention therefore relates to polyurethane compositions
comprising [0038] A) a polyisocyanate component, [0039] B) an
isocyanate-reactive component comprising hydroxy-functional
multiblock copolymers B1) of the type Y(X.sub.i--H).sub.n with i=1
to 10 and n=2 to 8 and number average molecular weights greater
than 1000 g/mol, the segments X.sub.i being composed in each case
of oxyalkylene units of the formula (I),
[0039] --CH.sub.2--CH(R)--O-- formula (I) [0040] in which [0041] R
is a hydrogen, alkyl or aryl radical which may also be substituted
or may be interrupted by heteroatoms (such as ether oxygens) [0042]
Y is the fundamental initiator [0043] and the proportion of the
segments X.sub.i, based on the total amount of the segments X.sub.i
and Y, accounts for at least 50% by weight, [0044] C) compounds
which have groups reacting under the action of actinic radiation
with ethylenically unsaturated compounds with polymerization
(radiation-curing groups) and are themselves free of NCO groups,
[0045] D) free radical stabilizers [0046] E) photoinitiators [0047]
F) optionally catalysts [0048] G) optionally auxiliaries and
additives.
[0049] Typical polyurethane compositions comprise:
5 to 93.999% by weight of the components B) according to the
invention, 1 to 60% by weight of component A), 5 to 70% by weight
of the component C), 0.001 to 10% by weight of photoinitiators E),
0 to 10% by weight of free radical stabilizers D), 0 to 4% by
weight of catalysts F), 0 to 70% by weight of auxiliaries and
additives G).
[0050] Preferably, the polyurethane compositions according to the
invention comprise
15 to 82.989% by weight of the components B) according to the
invention, 2 to 40% by weight of component A), 15 to 70% by weight
of the component C), 0.01 to 7.5% by weight of photoinitiators E),
0.001 to 2% by weight of free radical stabilizers D), 0 to 3% by
weight of catalysts F), 0 to 50% by weight of auxiliaries and
additives G).
[0051] Particularly preferably, the polyurethane compositions
according to the invention comprise
15 to 82.489% by weight of the components B) according to the
invention, 2 to 40% by weight of component A), 15 to 50% by weight
of the component C), 0.5 to 5% by weight of photoinitiators E),
0.01 to 0.5% by weight of free radical stabilizers D), 0.001 to 2%
by weight of catalysts F), 0 to 35% by weight of auxiliaries and
additives G).
[0052] Suitable compounds of the polyisocyanate component A) are
all aliphatic, cycloaliphatic, aromatic or araliphatic di- and
triisocyanates known per se to the person skilled in the art, it
being unimportant whether they were obtained by means of
phosgenation or by phosgene-free processes. In addition, the
relatively high molecular weight secondary products (oligo- and
polyisocyanates) of monomeric di- and/or triisocyanates having a
urethane, urea, carbodiimide, acylurea, isocyanurate, allophanate,
biuret, oxadiazinetrione, uretdione or iminooxadiazinedione
structure, which secondary products are well known per se to the
person skilled in the art, can also be used in each case
individually or in any mixtures with one another.
[0053] For example, suitable monomeric di- or triisocyanates are
butylene diisocyanate, hexamethylene diisocyanate (HDI), isophorone
diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI),
1,8-diisocyanato-4-(isocyanatomethyl)octane,
isocyanatomethyl-1,8-octane diisocyanate (TIN), 2,4- and/or
2,6-toluene diisocyanate.
[0054] Also possible is the use of isocyanate-functional
prepolymers having urethane, allophanate or biuret structures as
compounds of component A), as can be obtained in a manner known
well per se by reacting the abovementioned di-, tri- or
polyisocyanates in excess with hydroxy- or amino-functional
compounds. Any unreacted starting isocyanate can then be removed in
order to obtain low-monomer products. For accelerating the
prepolymer formation, use of catalysts well known to the person
skilled in the art per se from polyurethane chemistry may be
helpful.
[0055] Suitable hydroxy- or aminofunctional compounds for the
prepolymer synthesis are typically low molecular weight
short-chain, aliphatic, araliphatic or cycloaliphatic diols, triols
and/or higher polyols, i.e. containing 2 to 20 carbon atoms.
[0056] Examples of diols are ethylene glycol, diethylene glycol,
triethylene glycol, tetraethylene glycol, dipropylene glycol,
tripropylene glycol, 1,2-propanediol, 1,3-propanediol,
1,4-butanediol, neopentylglycol, 2-ethyl-2-butylpropanediol,
trimethylpentanediol, diethyloctanediol positional isomers,
1,3-butylene glycol, cyclohexanediol, 1,4-cyclohexanedimethanol,
1,6-hexanediol, 1,2- and 1,4-cyclohexanediol, hydrogenated
bisphenol A (2,2-bis(4-hydroxycyclohexyl)propane),
2,2-dimethyl-3-hydroxypropyl dimethyl-3-hydroxypropionate.
[0057] Examples of suitable triols are trimethylolethane,
trimethylolpropane or glycerol. Suitable higher-functional alcohols
are ditrimethylolpropane, pentaerythritol, dipentaerythritol or
sorbitol.
[0058] Relatively high molecular weight aliphatic and
cycloaliphatic polyols, such as polyester polyols, polyether
polyols, polycarbonate polyols, hydroxy-functional acrylic resins,
hydroxy-functional polyurethanes, hydroxy-functional epoxy resins
or corresponding hybrids (cf. Rompp Lexikon Chemie [Rompp Chemistry
Lexicon], pages 465-466, 10th edition 1998, Georg-Thieme-Verlag,
Stuttgart) are also suitable.
[0059] Polyesterpolyols suitable for the prepolymer synthesis are
linear polyester diols, as can be prepared in a known manner from
aliphatic, cycloaliphatic or aromatic di- or polycarboxylic acids
or their anhydrides, such as, for example, succinic, glutaric,
adipic, pimelic, suberic, azelaic, sebacic nonanedicarboxylic,
decanedicarboxylic, terephthalic, isophthalic, o-phthalic,
tetrahydrophthalic, hexahydrophthalic or trimellitic acid, and acid
anhydrides, such as o-phthalic, trimellitic or succinic anhydride,
or a mixture thereof with polyhydric alcohols, such as, for
example, ethanediol, di-, tri- or tetraethylene glycol,
1,2-propanediol, di-, tri-, or tetrapropylene glycol,
1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol,
1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol,
1,4-dihydroxycyclohexane, 1,4-dimethylolcyclohexane,
1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol or mixtures
thereof, optionally with concomitant use of higher functional
polyols, such as trimethylolpropane or glycerol. Of course,
cycloaliphatic and/or aromatic di- and polyhydroxy compounds are
also suitable as polyhydric alcohols for the preparation of the
polyester polyols. Instead of the free polycarboxylic acid, it is
also possible to use the corresponding polycarboxylic anhydrides or
corresponding polycarboxylates of lower alcohols or mixtures
thereof for the preparation of the polyesters.
[0060] Polyester polyols also suitable for the prepolymer synthesis
are homo- or copolymers of lactones, which are preferably obtained
by an addition reaction of lactones or lactone mixtures, such as
butyrolactone, s-caprolactone and/or methyl-.epsilon.-caprolactone,
with suitable difunctional and/or higher-functional initiator
molecules, such as, for example, the low molecular weight
polyhydric alcohols mentioned above as synthesis components for
polyester polyols.
[0061] Polycarbonates having hydroxyl groups are also suitable as a
polyhydroxy component for the prepolymer synthesis, for example
those which can be prepared by reaction of diols, such as
1,4-butanediol and/or 1,6-hexanediol and/or 3-methylpentanediol,
with diaryl carbonates, e.g. diphenyl carbonate, dimethyl carbonate
or phosgene.
[0062] Polyether polyols suitable for the prepolymer synthesis are,
for example, the polyaddition products of styrene oxides, of
ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide,
epichlorohydrin and their mixed adducts and graft products, and the
polyether polyols obtained by condensation of polyhydric alcohols
or mixtures thereof and those obtained by alkoxylation of
polyhydric alcohols, amines and amino alcohols. Preferred polyether
polyols are poly(propylene oxides), poly(ethylene oxides) and
combinations thereof in the form of random or block copolymers or
poly(tetrahydrofurans) and mixtures thereof having an OH
functionality of 1.5 to 6 and a number average molecular weight
between 200 and 18000 g/mol, preferably having an OH functionality
of 1.8 to 4.0 and a number average molecular weight of 600 to 8000
g/mol and particularly preferably having an OH functionality of 1.9
to 3.1 and a number average molecular weight of 650 to 4500
g/mol.
[0063] Suitable amines for the prepolymer synthesis are all
oligomeric or polymeric, primary or secondary, di-, tri- or
polyfunctional amines. For example, these may be: ethylenediamine,
diethylenetriamine, triethylenetetramine, propylenediamine,
diaminocyclohexane, diaminobenzene, diaminobisphenyl,
triaminobenzene, difunctional, trifunctional and higher-functional
polyamines, such as, for example, the Jeffamines.RTM.,
amine-terminated polymers having number average molar masses up to
10 000 g/mol or any mixtures thereof with one another.
[0064] Preferred prepolymers are those based on the abovementioned
synthesis components having urethane and/or allophanate groups with
number average molecular weights of 200 to 10 000 g/mol, preferably
with number average molecular weights of 500 to 8000 g/mol.
Particularly preferred prepolymers are allophanates based on HDI or
TMDI and di- or trifunctional polyether polyols having number
average molar masses of 1000 to 8000 g/mol.
[0065] It is, if appropriate, also possible for the isocyanate
component A to contain proportionate amounts of isocyanates which
are partly reacted with isocyanate-reactive ethylenically
unsaturated compounds. .alpha.,.beta.-Unsaturated carboxylic acid
derivatives, such as acrylates, methacrylates, maleates, fumarates,
maleimides, acrylamides, and vinyl ether, propenyl ether, allyl
ether and compounds which contain dicyclopentadienyl units having
at least one group reactive towards isocyanates are preferably used
here as isocyanate-reactive ethylenically unsaturated compounds.
Acrylates and methacrylates having at least one isocyanate-reactive
group are particularly preferred. Suitable hydroxy-functional
acrylates or methacrylates are, for example, compounds such as
2-hydroxyethyl(meth)acrylate, polyethylene oxide
mono(meth)acrylates, polypropylene oxide mono(meth)acrylates,
polyalkylene oxide mono(meth)acrylates,
poly(.epsilon.-caprolactone) mono(meth)acrylates, such as, for
example, Tone.RTM. M100 (Dow, USA), 2-hydroxypropyl(meth)acrylate,
4-hydroxybutyl(meth)acrylate,
3-hydroxy-2,2-dimethylpropyl(meth)acrylate, the hydroxy-functional
mono-, di- or tetra(meth)acrylates of polyhydric alcohols, such as
trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol,
ethoxylated, propoxylated or alkoxylated trimethylolpropane,
glycerol, pentaerythritol, dipentaerythritol and the industrial
mixtures thereof. In addition, isocyanate-reactive oligmeric or
polymeric unsaturated compounds containing acrylate and/or
methacrylate groups, alone or in combination with the
abovementioned monomeric compounds, are suitable. The proportion of
isocyanates which are partly reacted with isocyanate-reactive
ethylenically unsaturated compounds, based on the isocyanate
component A, is 0 to 99%, preferably 0 to 50%, particularly
preferably 0 to 25% and very particularly preferably 0 to 15%.
[0066] The NCO groups of the polyisocyanates of the component A)
can also be completely or partly blocked with the blocking agents
customary in industry. These are, for example, alcohols, lactams,
oximes, malonic esters, alkyl acetoacetates, triazoles, phenols,
imidazoles, pyrazoles and amines, such as, for example, butanone
oxime, diisopropylamine, 1,2,4-triazole, dimethyl-1,2,4-triazole,
imidazole, diethyl malonate, acetoacetates, acetone oxime,
3,5-dimethylpyrazole, .epsilon.-caprolactam,
N-tert-butylbenzylamine, cyclopentanonecarboxyethyl ester or any
mixtures of these blocking agents.
[0067] Polyisocyanates and/or prepolymers of the abovementioned
type based on HDI, TMDI and/or TIN are preferably used in A).
[0068] Polyisocyanates based on HDI with isocyanurate and/or
iminooxadiazinedione structures are particularly preferably
used.
[0069] The use of prepolymers, preferably having NCO
functionalities of 2 to 5, particularly preferably those having
primary NCO groups, is likewise particularly preferred. Examples of
such prepolymers are allophanates or urethanes or mixtures thereof,
preferably based on HDI and/or TMDI, and polyether- and/or
polyester- or polycarbonate polyols.
[0070] The abovementioned polyisocyanates or prepolymers preferably
have residual contents of free monomeric isocyanate of less than 1%
by weight, particularly preferably less than 0.5% by weight, very
particularly preferably less than 0.2% by weight.
[0071] The isocyanate-reactive component B1) has a multiblock
copolymer structure which satisfies the formula
Y(X.sub.i--H).sub.n.
[0072] The outer blocks X.sub.i account for at least 50% by weight,
preferably 66% by weight, of the total molar mass of
Y(X.sub.i--H).sub.n and consist of monomer units which obey the
formula (I). Preferably, n in Y(X.sub.i--H).sub.n is a number from
2 to 6, particularly preferably 2 or 3 and very particularly
preferably 2. Preferably, i in Y(X.sub.i--H).sub.n is a number from
1 to 6, particularly preferably from 1 to 3 and very particularly
preferably 1.
[0073] In formula (I), R is preferably a hydrogen, a methyl, butyl,
hexyl or octyl group or an alkyl radical containing ether group.
Preferred alkyl radicals containing ether groups are those based on
oxyalkylene units, the number of repeating units preferably being 1
to 50.
[0074] The multiblock copolymers Y(X.sub.i--H).sub.n preferably
have number average molecular weights of more than 1200 g/mol,
particularly preferably more than 1950 g/mol, but preferably not
more than 12 000 g/mol, particularly preferably not more than 9000
g/mol.
[0075] The blocks X.sub.i may be homopolymers comprising
exclusively identical oxyalkylene repeating units. They may also be
randomly composed of different oxyalkylene units or in turn
composed of blocks of different oxyalkylene units.
[0076] Preferably, the segments X.sub.i are based exclusively on
propylene oxide or random or blockwise mixtures of propylene oxide
with further 1-alkylene oxides, the proportion of further
1-alkylene oxides being not higher than 80% by weight.
[0077] Propylene oxide homopolymers and random or block copolymers
which oxyethylene, oxypropylene and/or oxybutylene units are
particularly preferred as segments X.sub.i, the proportion of the
oxypropylene units, based on the total amount of all oxyethylene,
oxypropylene and oxybutylene units, accounting for at least 20% by
weight, preferably at least 45% by weight.
[0078] The blocks X.sub.i are added, as described further below, to
an n-fold hydroxy- or aminofunctional starter block Y(H).sub.n by
ring-opening polymerization of the alkylene oxides described
above.
[0079] The inner block Y, which is present in an amount of less
than 50% by weight, preferably of less than 34% by weight, in
Y(X.sub.i--H).sub.n, consists of di- and/or
higher-hydroxy-functional polymer structures based on cyclic ethers
or is composed of di- and/or higher-hydroxy-functional
polycarbonate, polyester, poly(meth)acrylate, epoxy resin and/or
polyurethane structural units or corresponding hybrids.
[0080] Suitable polyester polyols are linear polyesterdiols or
branched polyesterpolyols, as can be prepared in a known manner
from aliphatic, cycloaliphatic or aromatic di- or polycarboxylic
acids or their anhydrides, such as, for example, succinic,
glutaric, adipic, pimelic, suberic, azelaic, sebacic,
nonanedicarboxylic, decanedicarboxylic, terephthalic, isophthalic,
o-phthalic, tetrahydrophthalic, hexahydrophthalic or trimellitic
acid, and acid anhydrides, such as o-phthalic, trimellitic or
succinic anhydride, or any mixtures thereof with polyhydric
alcohols, such as, for example, ethanediol, di-, tri- or
tetraethylene glycol, 1,2-propanediol, di-, tri-, or tetrapropylene
glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol,
2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol,
2,2-dimethyl-1,3-propanediol, 1,4-dihydroxycyclohexane,
1,4-dimethylolcyclohexane, 1,8-octanediol, 1,10-decanediol,
1,12-dodecanediol or mixtures thereof, optionally with the
concomitant use of higher-functional polyols, such as
trimethylolpropane or glycerol. Suitable polyhydric alcohols for
the preparation of the polyester polyols are of course also
cycloaliphatic and/or aromatic di- and polyhydroxy compounds.
Instead of the free polycarboxylic acid, it is also possible to use
the corresponding polycarboxylic anhydrides or corresponding
polycarboxylic esters of lower alcohols or mixtures thereof for the
preparation of the polyesters.
[0081] The polyester polyols may also be based on natural raw
materials, such as castor oil. It is also possible for the
polyester polyols to be based on mono- or copolymers of lactones,
as can preferably be obtained by an addition reaction of lactones
or lactone mixtures, such as butyrolactone, s-caprolactone and/or
methyl-.epsilon.-caprolactone, with hydroxy-functional compounds,
such as polyhydric alcohols having an OH functionality of
preferably 2, for example the abovementioned type.
[0082] Such polyester polyols preferably have number average molar
masses of 200 to 2000 g/mol, particularly preferably of 400 to 1400
g/mol.
[0083] Suitable polycarbonate polyols are obtainable in a manner
known per se by reacting organic carbonates or phosgene with diols
or diol mixtures.
[0084] Suitable organic carbonates are dimethyl, diethyl and
diphenyl carbonate.
[0085] Suitable diols or mixtures comprise the polyhydric alcohols
mentioned per se in connection with the polyester polyols and
having an OH functionality of 2, preferably 1,4-butanediol,
1,6-hexanediol and/or 3-methylpentanediol. Polyester polyols can
also be converted into polycarbonate polyols.
[0086] Such polycarbonate polyols preferably have number average
molar masses of 400 to 2000 g/mol, particularly preferably of 500
to 1400 g/mol and very particularly preferably of 650 to 1000
g/mol.
[0087] Suitable polyether polyols are optionally polyadducts of
cyclic ethers with OH-- or NH-functional initiator molecules, which
polyadducts have a block composition. For example, the polyadducts
of styrene oxides, of ethylene oxide, propylene oxide,
tetrahydrofuran, butylene oxide, epichlorhydrin and their mixed
adducts and graft products and the polyether polyols obtained by
condensation of polyhydric alcohols or mixtures thereof and those
obtained by alkoxylation of polyhydric alcohols, amines and
aminoalcohols may be as polyether polyols.
[0088] Suitable polymers of cyclic ethers are in particular
polymers of tetrahydrofuran.
[0089] Initiators which may be used are the polyhydric alcohols
mentioned per se in connection with the polyester polyols and
primary or secondary amines and amino alcohols having an OH or NH
functionality of 2 to 8, preferably 2 to 6, particularly preferably
2 or 3, very particularly preferably 2.
[0090] Such polyether polyols preferably have number average molar
masses of 200 to 2000 g/mol, particularly preferably of 400 to 1400
g/mol and very particularly preferably of 650 to 1000 g/mol.
[0091] Of course, mixtures of the components described above can
also be used for the inner block Y.
[0092] Preferred components for the inner block Y are polymers of
tetrahydrofuran and aliphatic polycarbonate polyols and polyester
polyols and polymers of .epsilon.-caprolactone having number
average molar masses of less than 3100 g/mol.
[0093] Particularly preferred components for the inner block Y are
difunctional polymers of tetrahydrofuran and difunctional aliphatic
polycarbonate polyols and polyester polyols and polymers of
.epsilon.-caprolactone having number average molar masses of less
than 3100 g/mol.
[0094] Very particularly preferably, the starter segment Y is based
on difunctional, aliphatic polycarbonate polyols,
poly(.epsilon.-caprolactone) or polymers of tetrahydrofuran having
number average molar masses greater than 250 g/mol and less than
2100 g/mol.
[0095] Preferably used block copolymers having the structure
Y(X.sub.i--H).sub.n comprise more than 50% by weight of the blocks
X.sub.i described above as being according to the invention and
have a total number average molar mass greater than 1200 g/mol.
[0096] Particularly preferred block copolymers comprise less than
50% by weight of aliphatic polyester, aliphatic polycarbonate
polyol or poly-THF and more than 50% by weight of the blocks
X.sub.i described above as being according to the invention and
have a number average molar mass greater than 1200 g/mol.
Particularly preferred block copolymers comprise comprise less than
50% by weight of aliphatic polycarbonate polyol,
poly(.epsilon.-caprolactone) or poly-THF and more than 50% by
weight of the blocks X.sub.i described above as being according to
the invention and have a number average molar mass greater than
1200 g/mol.
[0097] Very particularly preferred block copolymers comprise less
than 34% by weight of aliphatic polycarbonate polyol,
poly(.epsilon.-caprolactone) or poly-THF and more than 66% by
weight of the blocks X.sub.i described above as being according to
the invention and have a number average molar mass greater than
1950 g/mol and less than 9000 g/mol.
[0098] The block copolymers according to the invention are prepared
by alkylene oxide addition processes. Of industrial importance is
firstly the base-catalysed addition reaction of alkylene oxides
with initiator compounds having Zerewitinoff-active hydrogen atoms
Y(H).sub.n; secondly, the use of double metal cyanide compounds
("DMC catalysts") is becoming increasingly important for carrying
out this reaction. Hydrogen bonded to N, O or S is designated as
Zerewitinoff-active hydrogen (sometimes also only as "active
hydrogen") if it gives methane by reaction with methylmagnesium
iodide by a process discovered by Zerewitinoff. Typical examples of
compounds having a Zerewitinoff-active hydrogen are compounds which
contain carboxyl, hydroxyl, amino, imino or thiol groups as
functional groups. The base-catalysed addition reaction of alkylene
oxides, such as, for example, ethylene oxide or propylene oxide,
with initiator compounds having Zerewitinoff-active hydrogen atoms
is effected in the presence of alkali metal hydroxides, but it is
also possible to use alkali metal hydrides, alkali metal
carboxylates or alkaline earth metal hydroxides. After the addition
reaction of the alkylene oxides is complete, the
polymerization-active centres on the polyether chains must be
deactivated, for example by neutralizing with dilute mineral acids,
such as sulphuric acid or phosphoric acid, and separating off the
resulting salts. In the process according to the invention, DMC
catalysts are preferably used. Highly active DMC catalysts which
are described, for example, in U.S. Pat. No. 5,470,813, EP-A 700
949, EP-A 743 093, EP-A 761 708, WO 97/40086, WO 98/16310 and WO
00/47649 are particularly preferably used. The highly active DMC
catalysts which are described in EP-A 700 949 and, in addition to a
double metal cyanide compound (e.g. zinc hexacyanocobaltate(III))
and an organic complex ligand (e.g. tert-butanol), also contain a
polyether having a number average molecular weight greater than 500
g/mol are are a typical example. Owing to their high activity,
these catalysts can be used in such small amounts that further
work-up of the polyether polyols is not required. The process is
described in detail below. The "initiator polyol" used is always
the OH-functionalized precursor Y which is present in an amount of
less than 50% by weight in the block copolymer and onto which
alkylene oxide is polymerized so that at the end a multiblock
copolymer is obtained. Preferably obtained alkylene oxides are
ethylene oxide, propylene oxide, butylene oxide and mixtures
thereof. The synthesis of the polyether chains by alkoxylation can
be carried out, for example, only with one monomeric epoxide or
randomly or blockwise with a plurality of different monomeric
epoxides.
[0099] As further constituents of the isocyanate-reactive component
B), all OH-- and/or NH-functional compounds known to the person
skilled in the art can be used as B2). These are in particular di-
and higher-functional polyether polyols, the monomers of which do
not obey the formula (I), such as polyester polyols, polycarbonate
polyols, homo- or copolymers of lactones, hydroxy- or
aminefunctional polyacrylic resins and polyamines, such as, for
example, the Jeffamines.RTM. or other amine-terminated polymers and
(block) copolymers or mixtures thereof.
[0100] If mixtures of B1) and B2) are used in B), preferably at
least 80% by weight of B1) and not more than 20% by weight of B2),
particularly preferably at least 99% by weight of B1) and not more
than 1% by weight of B2) and very particularly preferably 100% by
weight of B1) are used.
[0101] Preferably, compounds having a refractive index
n.sub.D.sup.20>1.55, particularly preferably >1.58, are used
in C).
[0102] In component C), compounds such as
.alpha.,.beta.-unsaturated carboxylic acid derivatives, such as
acrylates, methacrylates, maleates, fumarates, maleimides,
acrylamides, and furthermore vinyl ether, propenyl ether, allyl
ether and compounds containing dicyclopentadienyl units and
olefinically unsaturated compounds, such as, for example, styrene,
.alpha.-methylstyrene, vinyltoluene, olefins, such as, for example,
1-octene and/or 1-decene, vinyl esters, (meth)acrylonitrile,
(meth)acrylamide, methacrylic acid and acrylic acid can be used.
Acrylates and methacrylates are preferred.
[0103] In general, esters of acrylic acid or methacrylic acid are
designated as acrylates or methacrylates. Examples of acrylates and
methacrylates which can be used are methyl acrylate, methyl
methacrylate, ethyl acrylate, ethyl methacrylate, ethoxyethyl
acrylate, ethoxyethyl methacrylate, n-butyl acrylat, n-butyl
methacrylate, tert-butyl acrylate, tert-butyl methacrylate, hexyl
acrylate, hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl
methacrylate, butoxyethyl acrylate, butoxyethyl methacrylate,
lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl
methacrylate, phenyl acrylate, phenyl methacrylate, p-chlorophenyl
acrylat, p-chlorophenyl methacrylate, p-bromophenyl acrylat,
p-bromophenyl methacrylate, 2,4,6-trichlorophenyl acrylate,
2,4,6-trichlorophenyl methacrylate, 2,4,6-tribromophenyl acrylate,
2,4,6-tribromophenyl methacrylate, pentachlorophenyl acrylate,
pentachlorophenyl methacrylate, pentabromophenyl acrylate,
pentabromophenyl methacrylate, pentabromobenzyl acrylate,
pentabromobenzyl methacrylate, phenoxyethyl acrylate, phenoxyethyl
methacrylate, phenoxyethoxyethyl acrylate, phenoxyethoxyethyl
methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate,
1,4-bis(2-thionaphthyl)2-butyl acrylate,
1,4-bis(2-thionaphthyl)-2-butyl methacrylate,
propane-2,2-diylbis[(2,6-dibromo-4,1-phenylene)oxy(2-{[3,3,3-tris(4-chlor-
ophenyl)propanoyl]oxy}propane-3,1-diyl)oxyethane-2,1-diyl]diacrylate,
bisphenol A diacrylate, bisphenol A dimethacrylate,
tetrabromobisphenol A diacrylate, tetrabromobisphenol A
dimethacrylate and the ethoxylated analogue compounds thereof,
N-carbazolyl acrylates, to mention only a selection of acrylates
and methacrylates which can be used.
[0104] Of course, urethane acrylates can also be used as component
C). Urethane acrylates are understood as meaning compounds having
at least one acrylic ester group which additionally have at least
one urethane bond. It is known that such compounds can be obtained
by reacting a hydroxy-functional acrylate with an
isocyanate-functional compound.
[0105] Examples of isocyanates which can be used for this purpose
are aromatic, araliphatic, aliphatic and cycloaliphatic di-, tri-
or polyisocyanates. It is also possible to use mixtures of such
di-, tri- or polyisocyanates. Examples of suitable di-, tri- or
polyisocyanates are butylene diisocyanate, hexamethylene
diisocyanate (HDI), isophorone diisocyanate (IPDI),
1,8-diisocyanato-4-(isocyanatomethyl)octane, 2,2,4- and/or
2,4,4-trimethylhexamethylene diisocyanate, the isomeric
bis(4,4'-isocyanatocyclohexyl)methanes and mixtures thereof having
any desired isomer content, isocyanatomethyl-1,8-octane
diisocyanate, 1,4-cyclohexylene diisocyanate, the isomeric
cyclohexanedimethylene diisocyanates, 1,4-phenylene diisocyanate,
2,4- and/or 2,6-toluene diisocyanate, 1,5-naphthylene diisocyanate,
2,4'- or 4,4'-diphenylmethane diisocyanate, 1,5-naphthylene
diisocyanate, triphenylmethane 4,4',4''-triisocyanate and
tris(p-isocyanatophenyl)thiophosphate or derivatives thereof having
a urethane, urea, carbodiimide, acylurea, isocyanurate,
allophanate, biuret, oxadiazinetrione, uretdione or
iminooxadiazinedione structure and mixtures thereof. Aromatic or
araliphatic di-, tri- or polyisocyanates are preferred.
[0106] Suitable hydroxyfunctional acrylates or methacrylates for
the preparation of urethane acrylates are, for example, compounds
such as 2-hydroxyethyl(meth)acrylate, polyethylene oxide
mono(meth)acrylates, polypropylene oxide mono(meth)acrylates,
polyalkylene oxide mono(meth)acrylates,
poly(.epsilon.-caprolactone) mono(meth)acrylates, such as, for
example, Tone.RTM. M100 (Dow, Schwalbach, Germany), 2-hydroxypropyl
(meth)acrylate, 4-hydroxybutyl(meth)acrylate,
3-hydroxy-2,2-dimethylpropyl (meth)acrylate,
hydroxypropyl(meth)acrylate, 2-hydroxy-3-phenoxypropyl acrylate,
the hydroxyfunctional mono-, di- or tetraacrylates of polyhydric
alcohols, such as trimethylolpropane, glycerol, pentaerythritol,
dipentaerythritol, ethoxylated, propoxylated or alkoxylated
trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol or
industrial mixtures thereof 2-Hydroxyethyl acrylate, hydroxypropyl
acrylate, 4-hydroxybutyl acrylate and poly(.epsilon.-caprolactone)
mono(meth)acrylates are preferred. In addition, as
isocyanate-reactive oligomeric or polymeric unsaturated compounds
containing acrylate and/or methacrylate groups, alone or in
combination with the abovementioned monomeric compounds, are
suitable. It is also possible to use the epoxy(meth)acrylates known
per se, containing hydroxyl groups and having OH contents of 20 to
300 mg KOH/g or polyurethane (meth)acrylates containing hydroxyl
groups and having OH contents of 20 to 300 mg KOH/g or acrylated
polyacrylates having OH contents of 20 to 300 mg KOH/g and mixtures
thereof with one another and mixtures with unsaturated polyesters
containing hydroxyl groups and mixtures with polyester
(meth)acrylates or mixtures of unsaturated polyesters containing
hydroxyl groups with polyester (meth)acrylates. Epoxyacrylates
containing hydroxyl groups and having a defined hydroxy
functionality are preferred. Epoxy(meth)acrylates containing
hydroxyl groups are based in particular on reaction products of
acrylic acid and/or methacrylic acid with epoxides (glycidyl
compounds) of monomeric, oligomeric or polymeric bisphenol A,
bisphenol F, hexanediol and/or butanediol or the ethoxylated and/or
propoxylated derivatives thereof. Epoxyacrylates having a defined
functionality, as can be obtained from the known reaction of
acrylic acid and/or methacrylic acid and glycidyl(meth)acrylate,
are furthermore preferred.
[0107] (Meth)acryltes and/or urethane (meth)acrylates are
preferably used, particularly preferably (meth)acrylates and/or
urethane (meth)acrylates which have at least one aromatic
structural unit.
[0108] Compounds particularly preferably to be used as component C
are urethane acrylates and urethane methacrylates based on aromatic
isocyanates and 2-hydroxyethyl acrylate, hydroxypropyl acrylate,
4-hydroxybutyl acrylate, polyethylene oxide mono(meth)acrylate,
polypropylene oxide mono(meth)acrylate, polyalkylene oxide
mono(meth)acrylate and poly(.epsilon.-caprolactone)
mono(meth)acrylates.
[0109] In a very particularly preferred embodiment, the adducts of
aromatic triisocyanates (very particularly preferably
tris(4-phenylisocyanato) thiophosphate or trimers of aromatic
diisocyanates, such as toluene diisocyanate) with hydroxyethyl
acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate are used
as component C. In a further very particularly preferred
embodiment, adducts of 3-thiomethylphenyl isocyanate with
hydroxyethyl acrylate, hydroxypropyl acrylate or 4-hydroxybutyl
acrylate are used as component C.
[0110] Examples of vinylaromatics are styrene, halogenated
derivatives of styrene, such as, for example, 2-chlorostyrene,
3-chlorostyrene, 4-chlorostyrene, 2-bromostyrene, 3-bromostyrene,
4-bromostyrene, p-(chloromethyl)styrene, p-(bromomethyl)styrene or
1-vinylnaphthalene, 2-vinylnaphthalene, 2-vinylanthracene,
9-vinylanthracene, 9-vinylcarbazole or difunctional compounds, such
as divinylbenzene.
[0111] Suitable compounds of component D) are, for example,
inhibitors and antioxidants, as described, for example, in
"Methoden der organischen Chemie [Methods of Organic Chemistry]"
(Houben-Weyl), 4th edition, volume XIV/1, page 433 et seq., Georg
Thieme Verlag, Stuttgart 1961. Suitable classes of substances are,
for example, phenols, such as, for example,
2,6-di-tert-butyl-4-methylphenol, cresols, hydroquinones, benzyl
alcohols, such as, for example, benzhydrol, optionally also
quinones, such as, for example, 2,5-di-tert-butylquinone,
optionally also aromatic amines, such as diisopropylamine or
phenothiazine.
[0112] 2,6-Di-tert-butyl-4-methylphenol, phenothiazine,
p-methoxyphenol, 2-methoxy-p-hydroquinone and benzhydrol are
preferred
[0113] One or more photoinitiators are used as component E). These
are usually initiators which can be activated by actinic radiation
and initiate polymerization of the corresponding polymerizable
groups. Photoinitiators are commercially sold compounds known per
se, a distinction being made between monomolecular (type I) and
bimolecular (type II) initiators. Furthermore, depending on the
chemical nature, these initiators are used for the free radical,
the anionic (or), the cationic (or mixed) forms of the
above-mentioned polymerizations.
[0114] (Type I) systems for free radical photopolymerization are,
for example, aromatic ketone compounds, e.g. benzophenones, in
combination with tertiary amines, alkylbenzophenones,
4,4'-bis(dimethylamino)benzophenone (Michler's ketone), anthrone
and halogenated benzophenones or mixtures of said types. (Type II)
initiators, such as benzoin and its derivatives, benzil ketals,
acylphosphine oxides, e.g. 2,4,6-trimethylbenzoyldiphenylphosphine
oxide, bisacylophosphine oxide, phenylglyoxylic esters,
camphorquinone, alpha-aminoalkylphenone,
alpha,alpha-dialkoxyacetophenone,
1-[4-(phenylthio)phenyl]octane-1,2-dione 2-(O-benzoyloxime) and
alpha-hydroxyalkylphenone are furthermore suitable. The
photoinitiator systems described in EP-A 0223587 and consisting of
a mixture of an ammonium arylborate and one or more dyes can also
be used as a photoinitiator. For example, tetrabutylammonium
triphenylhexylborate, tetrabutylammonium
tris-(3-fluorophenyl)hexylborate and tetrabutylammonium
tris(3-chloro-4-methylphenyl)hexylborate are suitable as ammonium
arylborate. Suitable dyes are, for example, new methylene blue,
thionine, basic yellow, pinacynol chloride, rhodamine 6G,
gallocyanine, ethyl violet, Victoria Blue R, Celestine Blue,
quinaldine red, crystal violet, brilliant green, Astrazon Orange G,
Darrow Red, pyronine Y, Basic Red 29, pyrillium I, cyanine and
methylene blue, Azure A (Cunningham et al., RadTech '98 North
America UV/EB Conference Proceedings, Chicago, Apr. 19-22,
1998).
[0115] The photoinitiators used for the anionic polymerization are
as a rule (type I) systems and are derived from transition metal
complexes of the first row. Chromium salts, such as, for example,
trans-Cr(NH.sub.3).sub.2(NCS).sub.4-- (Kutal et al., Macromolecules
1991, 24, 6872) or ferrocenyl compounds (Yamaguchi et al.,
Macromolecules 2000, 33, 1152) are known here. A further
possibility of the anionic polymerization consists in the use of
dyes, such as crystal violet leukonitrile or malachite green
leukonitrile, which can polymerize cyanoacrylates by photolytic
decomposition (Neckers et al. Macromolecules 2000, 33, 7761).
However, the chromophore is incorporated into the polymer so that
the resulting polymers are coloured through.
[0116] The photoinitiators used for the cationic polymerization
substantially comprise three classes: aryldiazonium salts, onium
salts (here in particular: iodonium, sulphonium and selenonium
salts) and organometallic compounds. Under irradiation, both in the
presence and the absence of a hydrogen donor, phenyldiazonium salts
can produced a cation that initiates the polymerization. The
efficiency of the total system is determined by the nature of the
counterion used for the diazonium compound. Here, the slightly
reactive but very expensive SbF.sub.6.sup.-, AsF.sub.6.sup.- or
PF.sub.6.sup.- is preferred. For use in coating thin films, these
compounds are as a rule not very suitable since the surface quality
is reduced (pinholes) by the nitrogen liberated after the exposure
to light (Li et al., Polymeric Materials Science and Engineering,
2001, 84, 139). Very widely used and also commercially available in
all kinds of forms are onium salts, especially sulphonium and
iodonium salts. The photochemistry of these compounds has long been
investigated. The iodonium salts first decompose homolytically
after excitation and thus produce a free radical and free radical
cation which is stabilized by H abstraction, liberates a proton and
then initiates the cationic polymerization (Dektar et al., J. Org.
Chem. 1990, 55, 639; J. Org. Chem., 1991, 56, 1838). This mechanism
enables the use of iodonium salts also for free radical
photopolymerization. The choice of the counterion is once again of
considerable importance here; very expensive SbF.sub.6.sup.-,
AsF.sub.6.sup.- or PF.sub.6.sup.- are likewise preferred.
Otherwise, in this structure class, the choice of the substitution
of the aromatic is completely free and is substantially determined
by the availability of suitable starting building blocks for the
synthesis. The sulphonium salts are compounds which decompose
according to Norrish(II) (Crivello et al., Macromolecules, 2000,
33, 825). In the case of the sulphonium salts, too, the choice of
the counterion is of critical importance, which manifests itself
substantially in the curing rate of the polymers. The best results
are obtained as a rule with SbF.sub.6.sup.- salts. Since the
self-absorption of iodonium and sulphonium salts is <300 nm,
these compounds must be appropriately sensitized for the
photopolymerization with near UV or short-wave visible light. This
is possible by the use of aromatics having a higher absorption,
such as, for example, anthracene and derivatives (Gu et al., Am.
Chem. Soc. Polymer Preprints, 2000, 41 (2), 1266) or phenothiazine
or derivatives thereof (Hua et al, Macromolecules 2001, 34,
2488-2494).
[0117] It may be advantageous also to use mixtures of these
compounds. Depending on the radiation source used for the curing,
the type and concentration of photoinitiator must be adapted in a
manner known to the person skilled in the art. The above-mentioned
adjustment with regard to the photopolymerization is easily
possible for a person skilled in the art in the form of routine
experiments within the below-mentioned quantity ranges of the
components and the respectively available, in particular the
preferred synthesis components.
[0118] Preferred photoinitiators E) are mixtures of
tetrabutylammonium tetrahexylborate, tetrabutylammonium
triphenylhexylborate, tetrabutylammonium
tris(3-fluorophenyl)hexylborate and tetrabutylammonium
tris(3-chloro-4-methylphenyl)hexylborate with dyes, such as, for
example, Astrazon Orange G, methylene blue, new methylene blue,
azure A, pyrillium I, safranine O, cyanine, gallocyanine, brilliant
green, crystal violet, ethyl violet and thionine.
[0119] Optionally, one or more catalysts may be used as compounds
of component F). These are catalysts for accelerating the urethane
formation. Known catalysts for this purpose are, for example, tin
octanoate, zinc octanoate, dibutyltin dilaurate,
dimethylbis[(1-oxoneodecyl)oxy]stannane, dimethyltin dicarboxylate,
zirconium bis(ethylhexanoate), zirconium acteylacetonate or
tertiary amines, such as, for example,
1,4-diazabicyclo[2.2.2]octane, diazabicyclononane,
diazabicycloundecane, 1,1,3,3-tetramethylguanidine,
1,3,4,6,7,8-hexahydro-1-methyl-2H-pyrimido(1,2-a)pyrimidine.
[0120] Dibutyltin dilaurate,
dimethylbis[(1-oxoneodecyl)oxy]stannane, dimethyltin dicarboxylate,
1,4-diazabicyclo[2.2.2]octane, diazabicyclononane,
diazabicycloundecane, 1,1,3,3-tetramethylguanidine,
1,3,4,6,7,8-hexahydro-1-methyl-2H-pyrimido(1,2-a)pyrimidine are
preferred.
[0121] Of course, further additives G) can optionally be used.
These may be, for example, additives customary in the area of
coating technology, such as solvents, plasticizers, levelling
agents or adhesion promoters. Plasticizers used are preferably
liquids having good dissolution properties, low volatility and a
high boiling point. It may also be advantageous simultaneously to
use a plurality of additives of one type. Of course, it may also be
advantageous to use a plurality of additives of a plurality of
types.
[0122] With the polyurethane compositions according to the
invention, holograms for optical applications in the entire visible
range and in the near UV range (300-800 nm) can be produced by
appropriate exposure processes. Visual holograms comprise all
holograms which can be recorded by methods known to the person
skilled in the art, including, inter alia, in-line (Gabor)
holograms, off-axis holograms, full-aperture transfer holograms,
whitelight transmission holograms ("rainbow holograms"), Denisyuk
holograms, off-axis reflection holograms, edge-literature holograms
and holographic stereograms; reflection holograms, Denisyuk
holograms and transmission holograms are preferred. Optical
elements, such as lenses, mirrors, deflection mirrors, filters,
diffusion screens, diffraction elements, light guides, waveguides,
projection screens and/or masks have are preferred. Frequently,
these optical elements show frequency selectivity depending on how
the holograms were exposed to light and which dimensions the
hologram has. The polyurethane compositions described are
particularly advantageous because, during their use, a high
refractive index contrast delta n.gtoreq.0.011 is achievable, which
is not achieved with the formulations described in the prior
art.
[0123] In addition, holographic images or diagrams can also be
produced by means of the polyurethane compositions according to the
invention, such as, for example, for personal portraits, biometric
representations in security documents or generally of images or
image structures for advertising, security labels, trademark
protection, trademark branding, labels, design elements,
decorations, illustrations, multi journey tickets, images and the
like, and images which can represent digital data, inter alia also
in combination with the products described above. Holographic
images may give the impression of a three-dimensional image but
they may also represent image sequences, short films or a number of
different objects, depending on the angle from which they are
illuminated, the light source (including moving light source) with
which they are illuminated, etc. Owing to these varied design
possibilities, holograms, in particular volume holograms, are an
attractive solution for the abovementioned application.
[0124] The present invention therefore further relates to the use
of the media according to the invention for recording visual
holograms, for producing optical elements, images, diagrams, and a
method for recording holograms using the polyurethane compositions
according to the invention, and the media or holographic films
obtainable therefrom.
[0125] The process according to the invention for the production of
holographic media for recording visual holograms is preferably
carried out in such a way that the synthesis components of the
polyurethane compositions according to the invention, with the
exception of component A), are homogeneously mixed with one another
and component A) is admixed only immediately before application to
the substrate or in the mould.
[0126] All methods and apparatuses known per se to the person
skilled in the art from mixing technology, such as, for example,
stirred tanks or both dynamic and static mixers, can be used for
mixing. However, apparatuses without dead spaces or with only small
dead spaces are preferred. Furthermore, preferred methods are those
in which the mixing is effected within a very short time and with
very thorough mixing of the two components to be mixed. In
particular, dynamic mixers are suitable for this purpose,
especially those in which the components come into contact with one
another only in the mixer.
[0127] The temperatures during the procedure are 0 to 100.degree.
C., preferably 10 to 80.degree. C., particularly preferably 20 to
60.degree. C.
[0128] If necessary, degassing of the individual components or the
entire mixture can also be carried out under reduced pressure of,
for example, 1 mbar. Degassing, in particular after addition of
component A), is preferred in order to prevent bubble formation by
residual gasses in the media obtainable.
[0129] Prior to admixing of component A), the mixtures can be
stored as a storage-stable intermediate, if required over several
months.
[0130] After the admixing of component A) of the polyurethane
compositions according to the invention, a clear, liquid
formulation is obtained which, depending on composition, cures at
room temperature within a few seconds to a few hours.
[0131] The ratio and the type and reactivity of the synthesis
components of the polyurethane compositions is preferably adjusted
so that the curing after admixing of component A) at room
temperature begins within minutes to one hour. In a preferred
embodiment, the curing is accelerated by heating after the admixing
to temperatures between 30 and 180.degree. C., preferably 40 to
120.degree. C., particularly preferably 50 to 100.degree. C.
[0132] The abovementioned adjustment with regard to the curing
behaviour is easily possible easily in the form of routine
experiments within the abovementioned quantity range of the
components and the synthesis components available for selection in
each case, in particular the preferred synthesis components.
[0133] Immediately after complete mixing of all components, the
polyurethane compositions according to the invention have
viscosities at 25.degree. C. of typically 10 to 100 000 mPas,
preferably 100 to 20 000 mPas, particularly preferably 200 to 10
000 mPas, especially preferably 500 to 5000 mPas, so that, even in
solvent-free form, they have very good processing properties. In
solution with suitable solvents, viscosities at 25.degree. C. below
10 000 mPas, preferably below 2000 mPas, particularly preferably
below 500 mPas, can be established.
[0134] Polyurethane compositions of the abovementioned type which
cure in an amount of 15 g and with a catalyst content of 0.004% by
weight at 25.degree. C. in less than 4 hours or at a catalyst
content of 0.02% in less than 10 minutes at 25.degree. C. have
proved to be advantageous.
[0135] For application to a substrate or into a mould, all
respective customary methods known to the person skilled in the art
are suitable, such as, in particular, knife coating, pouring,
printing, screen printing, spraying or inkjet printing.
[0136] All the references described above are incorporated by
reference in its entirety for all useful purposes.
[0137] While there is shown and described certain specific
structures embodying the invention, it will be manifest to those
skilled in the art that various modifications and rearrangements of
the parts may be made without departing from the spirit and scope
of the underlying inventive concept and that the same is not
limited to the particular forms herein shown and described.
EXAMPLES
[0138] The following examples are mentioned for explaining the
photopolymers according to the invention but are not to be
understood as being limiting. Unless noted otherwise, all stated
percentages are percentages by weight.
[0139] Desmodur.RTM. XP 2410 is an experimental product of Bayer
MaterialScience AG, Leverkusen, Germany, hexane diisocyanate-based
polyisocyanate, proportion of iminooxadiazinedione at least 30%,
NCO content: 23.5%
[0140] Desmodur.RTM. XP 2599 is an experimental product of Bayer
MaterialScience AG, Leverkusen, Germany, full allophanate of hexane
diisocyanate on Acclaim 4200, NCO content: 5.6-6.4%
[0141] Desmodur.RTM. XP 2580 is an experimental product of Bayer
MaterialScience AG, Leverkusen, Germany, aliphatic polyisocyanate
based on hexane diisocyanate, NCO content about 20%
[0142] Terathane.RTM. 650 is a commercial product of BASF AG,
Ludwigshafen, Germany (poly-THF having molar masses of 650
g/mol).
[0143] Terathane.RTM. 1000 is a commercial product of BASF AG,
Ludwigshafen, Germany (poly-THF having molar masses of 1000
g/mol).
[0144] Polyol 2 is a difunctional
poly(.epsilon.-caprolactone)polyol (number average molar mass about
650 g/mol).
[0145] Polyol 1 is an experimental product of Bayer MaterialScience
AG; the preparation is described below.
[0146] Polyols 3 to 5 are polyols according to the invention. Their
preparation is described below.
[0147] DMC catalyst: double metal cyanide catalyst based on zinc
hexacyanocobaltate (III), obtainable by the process described in
EP-A 700 949
[0148] Fomrez.RTM. UL28: urethanization catalyst,
dimethylbis[(1-oxoneodecl)oxy]stannane, commercial product of
Momentive Performance Chemicals, Wilton, Conn., USA (used as 10%
strength solution in N-ethylpyrrolidone).
[0149] CGI 909 is an experimental product sold in 2008 by Ciba
Inc., Basle, Switzerland.
[0150] Irganox 1076 is octadecyl
3,5-di(tert)butyl-4-hydroxyhydrocinnamate (CAS 2082-79-3).
[0151] Measurement of diffraction efficiency DE and refractive
index contrast .DELTA.n:
[0152] The media according to the invention and comparative media
produced in the experimental part were tested by means of a
measuring arrangement according to FIG. 1 with regard to their
holographic properties:
[0153] FIG. 1: Geometry of a holographic media tester at 2=633 nm
(He--Ne laser) for writing a reflection hologram: M=mirror,
S=shutter, SF=spatial filter, CL=collimator lens,
.lamda./2=.lamda./2 plate, PBS=polarization-sensitive beam
splitter, D=detector, I=iris diaphragm, .alpha.=21.8.degree. and
.beta.=41.8.degree. are the angles of incidence of the coherent
beams measured outside the sample (the medium).
[0154] The beam of an He--Ne laser (emission wavelength 633 nm) was
converted with the aid of the spatial filter (SF) and together with
the collimation lens (CL) into a parallel homogeneous beam. The
final cross sections of the signal and reference beam are
established by the iris diaphragms (I). The diameter of the iris
diaphragm opening is 4 mm The polarization-dependent beam splitters
(PBS) split the laser beam into two coherent equally polarized
beams. By the .lamda./2 plates, the power of the reference beam was
adjusted of 0.5 mW and the power of the signal beam to 0.65 mW. The
powers were determined using the semiconductor detectors (D) with
sample removed. The angle of incidence (.alpha.) of the reference
beam is 21.8.degree. and the angle of incidence (.beta.) of the
signal beam is 41.8.degree.. At the location of the sample
(medium), the interference field of the two overlapping beams
produced a grating of light and dark strips which are perpendicular
to the angle bisectors of the two beams incident on the sample
(reflection hologram). The strip spacing in the medium is
.about.225 nm (refractive index of the medium assumed to be
.about.1.49).
[0155] Holograms were written into the medium in the following
manner:
[0156] Both shutters (S) are opened for the exposure time t.
Thereafter, with shutters (S) closed, the medium was allowed a time
of 5 minutes for diffusion of the still unpolymerized writing
monomers. The holograms written were now read in the following
manner. The shutter of the signal beam remained closed. The shutter
of the reference beam was opened. The iris diaphragm of the
reference beam was closed to a diameter of <1 mm. This ensured
that the beam was always completely in the previously written
hologram for all angles (.OMEGA.) of rotation of the medium. The
turntable, under computer control, converted the angle range from
.OMEGA.=0.degree. to .OMEGA.=20.degree. with an angle step width of
0.05.degree.. At each angle approached, the powers of the beam
transmitted in the zeroth order were measured by means of the
corresponding detector D and the powers of the beam diffracted in
the first order were measured by means of the detector D. The
diffraction efficiency .eta. was obtained at each angle .OMEGA.
approached as the quotient of:
.eta. = P D P D + P T ##EQU00001##
[0157] P.sub.D is the power in the detector of the diffracted beam
and P.sub.T is the power in the detector of the transmitted
beam.
[0158] By means of the method described above, the Bragg curve (it
describes the diffraction efficiency .eta. as a function of the
angle .OMEGA. of rotation of the written hologram) was measured and
was stored in a computer. In addition, the intensity transmitted in
the zeroth order was also plotted against the angle .OMEGA. of
rotation and stored in a computer.
[0159] The maximum diffraction efficiency (DE=.eta..sub.max) of the
hologram, i.e. its peak value, was determined. It may have been
necessary for this purpose to change the position of the detector
of the diffracted beam in order to determine this maximum
value.
[0160] The refractive index contrast .DELTA.n and the thickness d
of the photopolymer layer were now determined by means of the
coupled wave theory (cf.: H. Kogelnik, The Bell System Technical
Journal, Volume 48, November 1969, Number 9, page 2909 page 2947)
from the measured Bragg curve and the variation of the transmitted
intensity as a function of angle. The method is described
below:
[0161] According to Kogelnik, the following is true for the Bragg
curve .eta./(.OMEGA.) of a reflection hologram:
.eta. = 1 1 + 1 - ( .chi. / .PHI. ) 2 sinh 2 ( .PHI. 2 - .chi. 2 )
##EQU00002## with : ##EQU00002.2## .PHI. = .pi. .DELTA. n d .lamda.
cos ( .alpha. ' ) cos ( .alpha. ' - 2 .psi. ) ##EQU00002.3## .chi.
= .DELTA..theta. 2 .pi. sin ( .alpha. ' - .psi. ) .LAMBDA. cos (
.alpha. ' - 2 .psi. ) d 2 ##EQU00002.4## .psi. = .beta. ' - .alpha.
' 2 ##EQU00002.5## .LAMBDA. = .lamda. 2 n cos ( .psi. - .alpha. ' )
##EQU00002.6## n sin ( .alpha. ' ) = sin ( .alpha. ) , n sin (
.beta. ' ) = sin ( .beta. ) ##EQU00002.7## .DELTA. .theta. = -
.DELTA. .OMEGA. 1 - sin 2 ( .alpha. ) n 2 - sin 2 ( .alpha. )
##EQU00002.8##
[0162] .PHI. is the grating thickness, .chi. is the detuning
parameter and .PSI. is the angle of tilt of the refractive index
grating which was written. .alpha.' and .beta.' correspond to the
angles .alpha. and .beta. during writing of the hologram, but in
the medium. .DELTA..THETA. is the angle detuning measured in the
medium, i.e. the deviation from the angle .alpha.'. .DELTA..OMEGA.
is the angle detuning measured outside the medium, i.e. the
deviation from the angle .alpha.. n is the average refractive index
of the photopolymer and was set at 1.504.
[0163] The maximum diffraction efficiency (DE=.eta..sub.max) is
then obtained for .chi.=0, i.e. .DELTA..OMEGA.=0, as:
D E = tanh 2 ( .PHI. ) = tanh 2 ( .pi. .DELTA. n d .lamda. cos (
.alpha. ' ) cos ( .alpha. ' - 2 .psi. ) ) ##EQU00003##
[0164] The measured data of the diffraction efficiency, the
theoretical Bragg curve and the transmitted intensity are shown in
FIG. 2 plotted against the centred angle of rotation
.OMEGA.-.alpha. shift. Since, owing to the geometric shrinkage and
the change in the average refractive index during the
photopolymerization, the angle at which DE is measured differs from
.alpha., the x axis is centred around this shift. The shift is
typically 0.degree. to 2.degree..
[0165] Since DE is known, the shape of the theoretical Bragg curve
according to Kogelnik is determined only by the thickness d of the
photopolymer layer. .DELTA.n is subsequently corrected via DE for a
given thickness d so that measurement and theory of DE always
agree. d is now adapted until the angle positions of the first
secondary minima of the theoretical Bragg curve agree with the
angle positions of the first secondary maxima of the transmitted
intensity and additionally the full width at half maximum (FWHM)
for the theoretical Bragg curve and the transmission intensity
agree.
[0166] Since the direction in which a reflection hologram
concomitantly rotates on reconstruction by means of an .OMEGA.
scan, but the detector for the diffracted light can detect only a
finite angle range, the Bragg curve of broad holograms (small d) is
not completely detected in an .OMEGA. scan, but only the central
region, with suitable detector positioning. That shape of the
transmitted intensity which is complementary to the Bragg curve is
therefore additionally used for adapting the layer thickness d.
[0167] FIG. 2: Plot of the Bragg curve .eta. according to Kogelnik
(dashed line), of the measured diffraction efficiency (solid
circles) and of the transmitted power (black solid line) against
the angle detuning .DELTA..OMEGA.. Since, owing to the geometric
shrinkage and the change in the average refractive index during the
photopolymerization, the angle at which DE is measured differs from
.alpha., the x axis is centred around this shift. The shift is
typically 0.degree. to 2.degree..
[0168] For a formulation, this procedure was possibly repeated
several times for different exposure times t on different media in
order to determine the energy dose of the incident laser beam at
which DE reaches the saturation value during writing of the
hologram. The average energy dose E is obtained as follows:
E ( mJ / cm 2 ) = 2 [ 0.50 mW + 0.67 mW ] t ( s ) .pi. 0.4 2 cm 2
##EQU00004##
[0169] The powers of the part-beams were adapted so that the same
power density is achieved in the medium at the angles .alpha. and
.beta. used.
Preparation of Polyol 1
[0170] 0.18 g of zinc octanoate, 374.8 g of .epsilon.-caprolactone
and 374.8 g of a difunctional polytetrahydrofuran polyether polyol
(equivalent weight 500 g/mol of OH) were initially introduced into
a 1 l flask and heated to 120.degree. C. and kept at this
temperature until the solids content (proportion of nonvolatile
constituents) was 99.5% by weight or more. Thereafter, cooling was
effected and the product was obtained as a waxy solid.
Preparation of Polyol 3
[0171] 2465 g of Terathane.RTM. 650 were weighed into a 20 l
reaction tank equipped with a stirrer and 450.5 mg of DMC catalyst
were added. Heating was then effected to 105.degree. C. with
stirring at about 70 rpm. By application of a vacuum and pressure
equilibration with nitrogen three times, air was exchanged for
nitrogen. After the stirrer speed had been increased to 300 rpm,
nitrogen was passed from below through the mixture for 72 minutes
with the vacuum pump running and at a pressure of about 0.1 bar.
Thereafter, a pressure of 0.3 bar was established by means of
nitrogen and 242 g of propylene oxide (PO) were passed in for
starting the polymerization. The pressure increased to 2.03 bar
thereby. After 8 minutes, the pressure had fallen to 0.5 bar again
and a further 12.538 kg of PO were metered in over a period of 2 h
11 min at 2.34 bar. 17 minutes after the end of the PO metering, a
vacuum was applied at a residual pressure of 1.29 and complete
degassing was effected. The product was stabilized by addition of
7.5 g of Irganox 1076 and obtained as a colourless, viscous liquid
(OH number: 27.8 mg KOH/g, viscosity at 25.degree. C.: 1165
mPas).
Preparation of Polyol 4
[0172] 2475 g of Terathane.RTM. 650 were weighed into a 20 l
reaction tank equipped with a stirrer and 452.6 mg of DMC catalyst
were added. Heating was then effected to 105.degree. C. with
stirring at about 70 rpm. By applying a vacuum and equilibrating
the pressure with nitrogen three times, air was exchanged for
nitrogen. After the stirrer speed had been increased to 300 rpm,
nitrogen was passed from below through the mixture for 57 minutes
with the vacuum pump running and at a pressure of about 0.1 bar.
Thereafter, a pressure of 0.5 bar was established by means of
nitrogen and 100 g of ethylene oxide (EO) and 150 g of PO were
passed in simultaneously for starting the polymerization. The
pressure increased to 2.07 bar thereby. After 10 minutes, the
pressure had fallen to 0.68 bar again and a further 5.116 kg of EO
and 7.558 kg of PO as a mixture were passed in over a period of 1 h
53 min at 2.34 bar. 31 minutes after the end of the epoxide
metering, a vacuum was applied at a residual pressure of 2.16 bar
and complete degassing was effected. The product was stabilized by
addition of 7.5 g Irganox 1076 and obtained as a slightly turbid
(TE(F) number 330), viscous liquid (OH number 27.1 mg KOH/g,
viscosity at 25.degree. C.: 1636 mPas).
Preparation of Polyol 5
[0173] 1707 g of a polycarbonate diol having a number average molar
mass of 650 g/mol, prepared by polycondensation of
(3-methyl)-1,5-pentanediol and diphenyl carbonate, were weighed
into a 20 l reaction tank equipped with a stirrer and 527 mg of DMC
catalyst were added. Heating to 130.degree. C. was then effected
with stirring at about 70 rpm. By application of a vacuum and
equilibration of the pressure with nitrogen three times, air was
exchanged for nitrogen. After the stirrer speed had been increased
to 300 rpm, nitrogen was passed from below through the mixture for
85 minutes with the vacuum pump running and at a pressure of about
0.1 bar. Thereafter, a pressure of 0.2 bar was established by means
of nitrogen and 174 g of PO were passed in for starting the
polymerization. The pressure increased to 2.26 bar thereby. After 6
minutes, the pressure had fallen to 0.55 bar again and a further
8.826 kg of PO were passed in over a period of 1 h 32 min at 1.36
bar. 22 minutes after the end of the PO metering, a vacuum was
applied at a residual pressure of 0.674 bar and complete degassing
was effected. The product was stabilized by addition of 5.27 g of
Irganox 1076 and obtained as a colourless, viscous liquid (OH
number 24.8 mg KOH/g, viscosity at 25.degree. C.: 1659 mPas).
Preparation of the Urethane Acrylate 1
[0174] 0.1 g of 2,6-di-tert-butyl-4-methylphenol, 0.05 g of
dibutyltin dilaurate (Desmorapid Z, Bayer MaterialScience AG,
Leverkusen, Germany) and 213.07 g of a 27% strength solution of
tris(p-isocyanatophenyl)thiophosphate in ethyl acetate
(Desmodur.RTM. RFE, product of Bayer MaterialScience AG,
Leverkusen, Germany) were initially introduced into a 500 ml
round-bottomed flask and heated to 60.degree. C. Thereafter, 42.37
g of 2-hydroxyethyl acrylate were added dropwise and the mixture
was still kept at 60.degree. C. until the isocyanate content had
fallen below 0.1%. Thereafter, cooling was effected and the ethyl
acetate was completely removed in vacuo. The product was obtained
as a semicrystalline solid.
[0175] For the production of the holographic media, the component
C, the component D (which can already be predissolved in the
component C) and optionally the component G are dissolved in the
component B, if required at 60.degree. C., after which 20 .mu.m
glass beads (e.g. from Whitehouse Scientific Ltd, Waverton,
Chester, CH3 7PB, United Kingdom) are added and thoroughly mixed.
Thereafter, the component E in pure form or in dilute solution in
NEP is weighed in in the dark or under suitable lighting and mixed
again for 1 minute. Heating is optionally effected to 60.degree. C.
in a drying oven for not more than 10 minutes. Component A is then
added and mixing is effected again for 1 minute. Subsequently, a
solution of the component F is added and mixing is effected again
for 1 minute. The mixture obtained is degassed with stirring at
<1 mbar for not more than 30 seconds, after which it is
distributed over 50.times.75 mm glass plates and these are each
covered with a further glass plate. The curing of the PU
formulation takes place under weights of 15 kg over several hours
(usually overnight). In some cases, the media are postcured in
light-tight packaging for a further 2 hours at 60.degree. C. The
thickness d of the photopolymer layer is 20 .mu.m, resulting from
the diameter of the glass spheres used. Since different
formulations having different starting viscosity and different
curing rate of the matrix lead to layer thicknesses d of the
photopolymer layer which are not always the same, d is determined
separately from the characteristics of the written holograms for
each sample.
Comparative Example 1 (Medium)
[0176] 8.89 g of the polyol 1 prepared as described above
(comparison for component B) were mixed with 3.75 g of urethane
acrylate 1 (component C), 0.15 g of CGI 909 and 0.015 g of new
methylene blue (together component E) at 60.degree. C. and 0.525 g
of N-ethylpyrrolidone (component G) so that a clear solution was
obtained. Thereafter, cooling to 30.degree. C. was effected, 1.647
g of Desmodur.RTM. XP 2410 (component A) were added and mixing was
effected again. Finally, 0.009 g of Fomrez.RTM. UL 28 (component F)
was added and mixing was effected briefly again. The liquid
material obtained was then poured onto a glass plate and covered
there with a second glass plate which was kept at a distance of 20
.mu.m by spacers. This test specimen was left at room temperature
and cured over 16 hours. Maximum .DELTA.n: 0.0101.
Comparative Example 2 (Medium)
[0177] 6.117 g of polyol 2 (comparison for component B) were mixed
with 3.75 g of urethane acrylate 1 (component C), 0.15 g of CGI 909
and 0.015 g of new methylene blue (together component E) at
60.degree. C. and 0.525 g of N-ethylpyrrolidone (component G) so
that a clear solution was obtained. Thereafter, cooling to
30.degree. C. was effected, 4.418 g of Baytec.RTM. WE 180
(component A) were added and mixing was effected again. Finally,
0.030 g of Fomrez.RTM. UL 28 (component F) was added and mixing was
effected briefly again. The liquid material obtained was then
poured onto a glass plate and covered there with a second glass
plate which was kept at a distance of 20 .mu.m by spacers. This
test specimen was left at room temperature and cured over 16 hours.
Maximum .DELTA.n: 0.0063.
Comparative Example 3 (Medium)
[0178] 7.342 g of Terathane 1000 (comparison for component B) were
mixed with 3.75 g of urethane acrylate 1 (component C), 0.15 g of
CGI 909 and 0.015 g of new methylene blue (together component E) at
60.degree. C. and 0.525 g of N-ethylpyrrolidone (component G) so
that a clear solution was obtained. Thereafter, cooling to
30.degree. C. was effected, 3.193 g of Desmodur.RTM. XP 2580
(component A) were added and mixing was effected again. Finally,
0.030 g of Fomrez.RTM. UL 28 (component F) was added and mixing was
effected briefly again. The liquid material obtained was then
poured onto a glass plate and covered there with a second glass
plate which was kept at a distance of 20 .mu.m by spacers. This
test specimen was left at room temperature and cured over 16 hours.
Maximum .DELTA.n: 0.0106.
Comparative Example 4 (Medium)
[0179] 1.129 g of polyether L800 (polypropylene oxide having a
number average molar mass of 200 g/mol) (comparison for component
B) were mixed with 3.081 g of urethane acrylate 1 (component C),
0.12 g of CGI 909 and 0.012 g of new methylene blue (together
component E) at 60.degree. C. and 0.431 g of N-ethylpyrrolidone
(component G) so that a clear solution was obtained. Thereafter,
cooling to 30.degree. C. was effected, 7.525 g of Desmodur.RTM. XP
2599 (component A) were added and mixing was effected again.
Finally, 0.0259 g of Fomrez.RTM. UL 28 (component F) was added and
mixing was effected briefly again. The liquid material obtained was
then poured onto a glass plate and covered there with a second
glass plate which was kept at a distance of 20 .mu.m by spacers.
This test specimen was left at room temperature and cured over 16
hours. Maximum .DELTA.n: 0.0096.
Example 1 (Medium)
[0180] 8.293 g of polyol 3 (component B) were mixed with 5.25 g of
urethane acrylate 1 (component C), 0.15 g of CGI 909 and 0.015 g of
new methylene blue (together component E) at 60.degree. C. and
0.525 g of N-ethylpyrrolidone (component G) so that a clear
solution was obtained. Thereafter, cooling to 30.degree. C. was
effected, 0.743 g of Desmodur.RTM. XP 2410 (component A) was added
and mixing was effected again. Finally, 0.0140 g of Fomrez.RTM. UL
28 (component F) was added and mixing was effected briefly again.
The liquid material obtained was then poured onto a glass plate and
covered there with a second glass plate which was kept at a
distance of 20 .mu.m by spacers. This test specimen was left at
room temperature and cured over 16 hours. Maximum .DELTA.n:
0.0196.
Example 2 (Medium)
[0181] 7.711 g of polyol 3 (component B) were mixed with 3.75 g of
urethane acrylate 1 (component C), 0.15 g of CGI 909 and 0.015 g of
new methylene blue (together component E) at 60.degree. C. and
0.525 g of N-ethylpyrrolidone (component G) so that a clear
solution was obtained. Thereafter, cooling to 30.degree. C. was
effected, 2.823 g of Desmodur.RTM. XP 2599 (component A) were added
and mixing was effected again. Finally, 0.0389 g of Fomrez.RTM. UL
28 (component F) was added and mixing was effected briefly again.
The liquid material obtained was then poured onto a glass plate and
covered there with a second glass plate which was kept at a
distance of 20 .mu.m by spacers. This test specimen was left at
room temperature and cured over 16 hours. Maximum .DELTA.n:
0.0125.
Example 3 (Medium)
[0182] 8.827 g of polyol 3 (component B) were mixed with 4.5 g of
urethane acrylate 1 (component C), 0.15 g of CGI 909 and 0.015 g of
new methylene blue (together component E) at 60.degree. C. and
0.525 g of N-ethylpyrrolidone (component G) so that a clear
solution was obtained. Thereafter, cooling to 30.degree. C. was
effected, 0.958 g of Desmodur.RTM. XP 2580 (component A) was added
and mixing was effected again. Finally, 0.0255 g of Fomrez.RTM. UL
28 (component F) was added and mixing was effected briefly again.
The liquid material obtained was then poured onto a glass plate and
covered there with a second glass plate which was kept at a
distance of 20 .mu.m by spacers. This test specimen was left at
room temperature and cured over 16 hours. Maximum .DELTA.n:
0.0206.
Example 4 (Medium)
[0183] 9.533 g of polyol 4 (component B) were mixed with 3.75 g of
urethane acrylate 1 (component C), 0.15 g of CGI 909 and 0.015 g of
new methylene blue (together component E) at 60.degree. C. and
0.525 g of N-ethylpyrrolidone (component G) so that a clear
solution was obtained. Thereafter, cooling to 30.degree. C. was
effected, 1.001 g of Desmodur.RTM. XP 2580 (component A) were added
and mixing was effected again. Finally, 0.0342 g of Fomrez.RTM. UL
28 (component F) was added and mixing was effected briefly again.
The liquid material obtained was then poured onto a glass plate and
covered there with a second glass plate which was kept at a
distance of 20 .mu.m by spacers. This test specimen was left at
room temperature and cured over 16 hours. Maximum .DELTA.n:
0.0182.
Example 5 (Medium)
[0184] 9.611 g of polyol 5 (component B) were mixed with 3.75 g of
urethane acrylate 1 (component C), 0.15 g of CGI 909 and 0.015 g of
new methylene blue (together component E) at 60.degree. C. and
0.525 g of N-ethylpyrrolidone (component G) so that a clear
solution was obtained. Thereafter, cooling to 30.degree. C. was
effected, 0.924 g of Desmodur.RTM. XP 2580 (component A) was added
and mixing was effected again. Finally, 0.0300 g of Fomrez.RTM. UL
28 (component F) was added and mixing was effected briefly again.
The liquid material obtained was then poured onto a glass plate and
covered there with a second glass plate which was kept at a
distance of 20 .mu.m by spacers. This test specimen was left at
room temperature and cured over 16 hours. Maximum .DELTA.n:
0.0185.
* * * * *